Energy Code Basics: Is It an Alteration or an Addition?

By Alex Rippere

With all the changes in the latest New York City Energy Conservation Code (2016 NYCECC), it can be helpful to review some of the fundamental compliance issues faced by architects, engineers, and owners. For instance, understanding your project’s type—alteration, addition, a combination of the two, or new construction—is a crucial first step toward establishing a code compliance path that makes DOB approval as painless as possible. While it sounds simple, I have yet to encounter a project that grasped the nuances of this concept from inception.

Let’s start with definitions.

Alterations & Additions Defined

Chapter C2 of the 2016 NYCECC defines an alteration as:

Any construction, retrofit or renovation to an existing structure other than repair or addition that requires a permit. Also, a change in a building, electrical, gas, mechanical or plumbing system that involves an extension, addition or change to the arrangement, type or purpose of the original installation that requires a permit.

TRANSLATION: Does our job require a permit from DOB? If “yes,” it is at least an alteration.

The same chapter of the 2016 NYCECC defines addition as:

An extension or increase in the conditioned floor area or height of a building or structure.

TRANSLATION: Are we adding new conditioned floor space outside of our existing building’s bulk? If “yes,” it’s an addition.

So what’s the big deal between the two?

Compliance Implications

Additions. Broadly speaking, additions must comply with new construction requirements, such as fully insulated walls and roofs that comply with tables in NYCECC C402 or ASHRAE Section 5 (Table 5.5-4 governs NYC’s climate zone). For this reason, installing a glassy extension on our building could trigger an energy model; the addition itself will be subject to the 40% maximum clear fenestration limitation, requiring major trade-offs on the lighting and MEP side if we exceed this limit.

Also, additions to historic structures are not exempt. Neither NYCECC C501.6 nor ASHRAE Exception 1 references the word “addition.” Only work done inside the existing structure is entirely energy code exempt.

Additions and alterations. What is the easiest way to show compliance if we want to alter and enlarge a space or building? We can simply do two envelope COMchecks: one for the altered portion and one for the addition. All our favorite exceptions for alterations are already built into COMcheck, and the system will ask us if we increase the clear glazing area beyond the 40% maximum, which triggers energy modeling, or if we expose any uninsulated wall cavities, which would trigger cavity insulation.

As mentioned above, energy modeling offers an option if things get too glassy. ASHRAE Table 11.5.1, Item 2, lays out the requirements for breaking out an addition from the base building. Essentially, any addition must share common HVAC control systems with the base building to minimize the temperature difference between them. Sharing climate controls prevents massive heat loss or gain through the addition, since heat only goes where it’s colder. However, the actual HVAC systems must be separate. Including our base building boiler or cooling plant in the energy model would exceed the allowed energy costs for our tiny glass addition, keeping us in DOB disapproved status.

Alterations. Generally, alterations do not have to comply with new construction requirements for the exterior envelope, provided they do not increase energy use, with one mega exception: converting unconditioned space to conditioned space. NYCECC C503.2 dictates that “any nonconditioned or low-energy space that is altered to become conditioned space shall be required to be brought into full compliance with this code.” The key word here is “full.” In other words, the alteration exceptions allowing the walls to escape full insulation do not necessarily apply when converting unconditioned space to conditioned space.

ASHRAE is even more explicit: Changes in Space Conditioning. Whenever unconditioned or semiheated spaces in a building are converted to conditioned spaces, such conditioned spaces shall be brought into compliance with all the applicable requirements of this standard that would apply to the building envelope, heating, ventilating, air-conditioning, service water heating, power, lighting, and other systems and equipment of the space as if the building were new [emphasis added].

While completely unconditioned spaces and buildings are rare in NYC, they do pop up from time to time. Converting an unheated parking garage? Might as well check the “new construction” box on COMcheck and remove the word “alteration” from our vocabulary. Our converted garage will have to comply with the energy code as if “hereafter erected.”